Boosting interfacial Li+ transport with a MOF-based ionic conductor for solid-state batteries

Abstract Concerning the large interfacial resistance of materials within solid-stated batteries (SSBs) caused by the unstable solid contact, an assistant ionic conductor is introduced to improve the interfacial Li + transport of SSBs. The assistant ionic conductor is achieved by impregnating an ionic liquid (Li-IL) into a porous metal-organic framework (MOF) host. When integrated with LLZO solid-state electrolyte (SSE), the solidified Li-IL guest can make direct contact with the LLZO particles through the open channels in MOF host, which changes the original unstable solid-solid contact into “nanowetted” interfaces to boost Li + transport. Benefited from the unique nanowetted interfaces, the hybrid SSE demonstrates a high ionic conductivity of 1.0 × 10 −4 S cm −1 with a wide electrochemical window of 5.2 V, and also exhibits excellent compatibility with Li metal anode. Furthermore, the LLZO based LiCoO 4 and LiFePO 4 SSBs with the ionic conductor additive to favor the interfacial Li + transport achieve high capacity retention of 97% after 150 cycles with reasonable rate capability. The good electrochemical performance is attributed to the effective Li + transport networks established inside the SSBs by the ionic conductor through the nanowetted interfacial mechanism, which is proved to be a promising approach to the safe and high-power energy storage.